Add support for custom certificate key types via environment variables

This change allows users to specify custom key types and elliptic curves
for SSL certificates through CERT_KEY_TYPE and CERT_ELLIPTIC_CURVE
environment variables. This enables support for ECDSA P-256 certificates
and other key types.

When these environment variables are empty or not set, the current
default behavior is preserved, ensuring backward compatibility.

The environment variables are passed as arguments to certbot when
generating or renewing certificates for both HTTP and DNS challenges.

Author: mz2

backend/internal/certificate.js

@@ -857,6 +857,16 @@ const internalCertificate = {
 			certificate.domain_names.join(','),
 		];
 
+		// Add key type options if specified via environment variables
+		if (process.env.CERT_KEY_TYPE) {
+			args.push('--key-type', process.env.CERT_KEY_TYPE);
+			logger.info(`Using key type: ${process.env.CERT_KEY_TYPE}`);
+		}
+		if (process.env.CERT_ELLIPTIC_CURVE) {
+			args.push('--elliptic-curve', process.env.CERT_ELLIPTIC_CURVE);
+			logger.info(`Using elliptic curve: ${process.env.CERT_ELLIPTIC_CURVE}`);
+		}
+
 		const adds = internalCertificate.getAdditionalCertbotArgs(certificate.id);
 		args.push(...adds.args);
 
@@ -907,6 +917,16 @@ const internalCertificate = {
 			dnsPlugin.full_plugin_name,
 		];
 
+		// Add key type options if specified via environment variables
+		if (process.env.CERT_KEY_TYPE) {
+			args.push('--key-type', process.env.CERT_KEY_TYPE);
+			logger.info(`Using key type: ${process.env.CERT_KEY_TYPE}`);
+		}
+		if (process.env.CERT_ELLIPTIC_CURVE) {
+			args.push('--elliptic-curve', process.env.CERT_ELLIPTIC_CURVE);
+			logger.info(`Using elliptic curve: ${process.env.CERT_ELLIPTIC_CURVE}`);
+		}
+
 		if (hasConfigArg) {
 			args.push(`--${dnsPlugin.full_plugin_name}-credentials`, credentialsLocation);
 		}

docker/Dockerfile

@@ -23,7 +23,9 @@ ENV SUPPRESS_NO_CONFIG_WARNING=1 \
 	NPM_BUILD_VERSION="${BUILD_VERSION}" \
 	NPM_BUILD_COMMIT="${BUILD_COMMIT}" \
 	NPM_BUILD_DATE="${BUILD_DATE}" \
-	NODE_OPTIONS="--openssl-legacy-provider"
+	NODE_OPTIONS="--openssl-legacy-provider" \
+	CERT_KEY_TYPE="" \
+	CERT_ELLIPTIC_CURVE=""
 
 RUN echo "fs.file-max = 65535" > /etc/sysctl.conf \
 	&& apt-get update \